Chapters 48 and 49 Flashcards
Flow of information
dendrite -> cell body -> axon
Dendrite
collects electrical signals
Cell Body
integrates signals and generates an outgoing signal
Axon
passes signals to dendrites of another cell/effector cell
Signals
action potentials (AP)
- goes on in every neuron
- once started, cant be stopped
Resting membrane potential
chemical and electrical driving forces = potential energy
-create a voltage across the membrane
Vm= -70 mV
Chemical driving force for K+
larger
Na+ gradient
Na+ wants to move more
-2 gradients, the bigger gradient wins
Voltage
= current x resistance
Depolarization event in neuron
- Na depolarizes
- Ca releases the NT
- K repolarizes
Na channels
depolarize
-detect the threshold
K channels
repolarize
Synapse
- presynaptic membrane (neuron)
- presynaptic cleft
- postsynaptic membrane (effector cell)
Order of events
- Stimulus
- Graded potential: stimulus to the axon hillock
- Action potential
- Release of NT @ terminus
Ion Channels
-ligand gated on soma
-voltage gated on axon
Na+ or K+ or Ca+ selective
Action potential events
- Vg Na open (Na enters)
-depolarization - Vg Na close
Vg K open (K exits)
-repolarization - Vg K stay open
-hyperpolarization - Vg K close, Na and K leak out
Quanta
unit that NT are released in
All or nothing
AP’s
get the hillock to -55mV
Summation
sum of graded potentials to create an AP
- spatial
- temporal
Temporal summation
increased frequency, get further
Events at synapse
- Excitatory
- Inhibitory
Excitatory
depolarize, open Na+ channel
Inhibitory
hyper polarize, K or Cl channel
Long Term Potentiation at synapse
(LTP)
- AMPA receptor into membrane because of 2nd action potential
- more than one axon in a circuit, represents some memory
Forebrain
cerebrum
thalamus
hypothalamus
Hindbrain
pons
medulla oblongata
cerebellum
Pituitary gland
part neural and part glandular tissue
Meningies
hold brain and CSF
- fluid makes brain lighter
- w/o CSF the brain would crush itself
Gray matter
-neuron cell bodies
-short axon
-no myelin
CNS: nuclei
PNS: ganglia
White matter
-bundles of axons
-myelination
CNS: tracts
PNS: nerves
Cerebrum
- about 80% of the brain
- 3 layers
3 Layers of the Cerebrum
- outter grey
- middle white
- deep nuclei (grey)
Outer grey
sea of consciousness
Middle white
tracts
Deep nuclei
basal nuclei
- motor control
- consciousness
Gyri and sulci
ridges and valleys
-correlates to intelligence
Diencephalon
- epithalamus
- thalamus
- hypothalamus
- pit gland
Epithalamus
pineal gland= melatonin
Thalamus
- junction box
- connect cerebrum to lower brain and spinal cord
Hypothalamus
- autonomic control center
- thirst, body temp, endocrine, behavioral, anger, sex drive
- limbic system
Limbic system
stress mediated thru hypothalamus
-anger, sex drive
Pituitary gland
endocrine control
Midbrain
tracts connect to cerebellum
-cranial nerves
Pons
tracts:
- cerebrum
- cerebellum
- cardiovascular center
- respiratory center
Medulla Oblongata
- decussation
- heart rate
- ventilation
- reflexes: cough, sneeze, emesis, hiccups
Decussation
90% of the spinal tracts switch to the other side of the body
Cerebellum
coordination of motor control of skeletal muscle
Reticular formation
sleeping and waking
Lobes of the cerebrum
- insula
- frontal
- temporal
- parietal
- occipital
Insula
equilibrium
Frontal
- decision making
- skeletal muscles
Temporal
- hearing
- comprehending language
Parietal
sensory
Occipital
visual